Wireless communication networks are widely deployed to provide various communication services such as data, voice, video, and so on. These wireless networks include wireless wide area networks (WWANs) that provide communication coverage for large geographic areas (e.g., cities), wireless local area networks (WLANs) that provide communication coverage for medium-size geographic areas (e.g., buildings), and wireless personal area networks (WPANs) that provide communication coverage for small geographic areas (e.g., homes).
IEEE 802.11 is a family of standards developed by The Institute of Electrical and Electronics Engineers (IEEE) for WLANs. These standards cover medium range radio technologies. IEEE Std 802.11 1999 Edition (or simply, “802.11”) supports data rates of 1 and 2 mega bits/second (Mbps) in the 2.4 giga Hertz (GHz) frequency band using frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS). IEEE Std 802.11a-1999 (or simply, “802.11a”) supports data rates of 6 to 54 Mbps in the 5 GHz frequency band using orthogonal frequency division multiplexing (OFDM). IEEE Std 802.11b-1999 (or simply, “802.11b”) supports data rates of 1 to 11 Mbps in the 2.4 GHz band using DSSS. IEEE Std 802.11g-2003 (or simply, “802.11g”) supports data rates of 1 to 54 Mbps in the 2.4 GHz band using DSSS and OFDM. These various IEEE 802.11 standards are known in the art and publicly available.
The lowest data rate supported by the IEEE 802.11 standards is 1 Mbps. A certain minimum signal-to-noise-and-interference ratio (SNR) is required for reliable reception of a transmission sent at the lowest data rate of 1 Mbps. The range of the transmission is then determined by the geographic area within which a receiving station can achieve the required SNR or better. In certain instances, it is desirable to send a transmission with a range that is greater than the range for the lowest data rate supported by the IEEE 802.11 standards. Furthermore, it is desirable to achieve the greater transmission range with minimum increase in hardware complexity at both the transmitting and receiving stations.
There is therefore a need in the art for cost-effective techniques to extend the transmission range for a WLAN.